Java Web Lightweight Development Interview Tutorial reading notes: Database aspects, how to prepare for the interview

If you are able to effectively and reasonably demonstrate some of the knowledge points given in this chapter during an interview or with a senior personnel exchange, you will be evaluated as "in-depth knowledge of the database" and even with "experience in designing data sheets", even if you say that you have 3 years of experience in database operations for a business project, then others can believe it.

Conversely, if a programmer who has worked for 3 years may be able to do a good job of programming, but cannot prove it in the communication process, or simply do not know how to prove it, then the evaluation may often be "database level, experience with commercial projects, But only a few basic additions and deletions (at most, plus the view stored procedures and other technologies), can not be independent of the work of the database. "

The following is a list of common database interview questions, you can use this to measure the knowledge of this chapter of the degree of mastery.

Question 1, do you have any experience in building a table? Do you follow the three paradigms when building a table?

When designing a data table, you need to weigh the data redundancy and connection costs, please refer to section 2.1.3 for your description.

Question 2, what database optimization experience have you had?

You can say that you have used the index, specific points of knowledge can refer to section 2.3.

Question 3, please describe the scenario that should not be indexed.

Question 4,like statement will not go index?

Question 5, what is the structure of the index? What is the cost of building an index? How should we weigh the index?

For the above three questions, the cost can be referred to in section 2.3 of the description.

Question 6, what are the levels of the transaction isolation level? What is the meaning of specific dirty reads, Phantom reads, and non-repeatable reads?

Refer to section 2.4.4 for a description.

What is the difference between a problem 7,statement and a PreparedStatement object?

You can answer these two angles around preprocessing and batch processing.

The following we listed some of the more advanced database knowledge points, these knowledge points need to rely on project experience to precipitate, general senior programmer can know, and beginners or junior programmers may not know, you can in the interview, find the right opportunity to say, so the interviewer will be very impressed with you.

Knowledge point 1, in the database programming, try to use the try...catch...finally code structure, while in the finally put the release database connection resources such as code, because if we do not actively shut down the database connection, This portion of memory is not actively reclaimed by the garbage collector (GC).

Knowledge point 2, in order to improve the performance of the database operation, I will use the PreparedStatement to do batch operations, but the number of SQL statements per batch can not be too much, otherwise it will burst the buffer, generally each batch is about 500.

Knowledge point 3, through the preprocessing mechanism of preparedstatement, we can effectively prevent SQL injection.

Read the Java Web Lightweight Development Interview tutorial for more information

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Java Web Lightweight Development Interview Tutorial reading notes: Database aspects, how to prepare for the interview